Commit 20117b5a authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: move queue freezing & elevator_lock into elevator_change() 



Move queue freezing & elevator_lock into elevator_change(), and prepare
for using elevator_change() for setting up & tearing down default elevator
too.

Also add lockdep_assert_held() in __elevator_change() because either
read or write lock is required for changing elevator.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Reviewed-by: default avatarNilay Shroff <nilay@linux.ibm.com>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250505141805.2751237-15-ming.lei@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 596dce11

block/elevator.c

+12 −8
Original line number Diff line number Diff line
@@ -676,10 +676,19 @@ static int elevator_switch(struct request_queue *q, const char *name) 
 */

static int elevator_change(struct request_queue *q, const char *elevator_name)

{

	if (q->elevator && elevator_match(q->elevator->type, elevator_name))

		return 0;

	unsigned int memflags;

	int ret = 0;



	lockdep_assert_held(&q->tag_set->update_nr_hwq_lock);



	return elevator_switch(q, elevator_name);

	memflags = blk_mq_freeze_queue(q);

	mutex_lock(&q->elevator_lock);

	if (!(q->elevator && elevator_match(q->elevator->type,

				elevator_name)))

		ret = elevator_switch(q, elevator_name);

	mutex_unlock(&q->elevator_lock);

	blk_mq_unfreeze_queue(q, memflags);

	return ret;

}



/*
@@ -718,7 +727,6 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf, 
	char elevator_name[ELV_NAME_MAX];

	char *name;

	int ret;

	unsigned int memflags;

	struct request_queue *q = disk->queue;

	struct blk_mq_tag_set *set = q->tag_set;
@@ -737,13 +745,9 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf, 
	elv_iosched_load_module(name);



	down_read(&set->update_nr_hwq_lock);

	memflags = blk_mq_freeze_queue(q);

	mutex_lock(&q->elevator_lock);

	ret = elevator_change(q, name);

	if (!ret)

		ret = count;

	mutex_unlock(&q->elevator_lock);

	blk_mq_unfreeze_queue(q, memflags);

	up_read(&set->update_nr_hwq_lock);

	return ret;

}